Clark's Levels of Invasion:
Level 1 - Melanoma cells only in the epidermis (in-situ, non-invasive)
- growing and spreading on the surface of the skin only - see picture
Level 2 - Invasion of papillary dermis by melanoma cells (less than 10 cells wide)
- growing and spreading on the surface of the skin but also growing deeper through the second layer
Level 3 - Tumor cells expand and fill the papillary dermis
- growing and spreading deeply through the first two layers of the skin
Level 4 - Tumor cells grow down into the reticular dermis- third layer of the skin
Level 5 - Tumor cells grow down into the subcutaneous tissue- the fat layers
Thickness is the most important prognostic feature - the thicker it is, the worse it is.
Depth of invasion is measured in millimetres from the top of the mole to the deepest melanoma cell.
Less than 1 mm - usually no lymph node involvement
Greater than 4 mm - high risk that lymph nodes are positive for melanoma cells
Mine was 2 mm.
|Breslow Thickness||Approximate 5 year survival|
|1 - 2 mm||80-96%|
|2.1 - 4 mm||60-75%|
There are different types of melanoma - mine was called Nodular.
Nodular Melanoma is the fastest growing and it likes to go deep. It may or may not grow on an existing mole. Usually it is a new spot. They are mostly dark, but can be light - mine was light and it grew on top of an existing mole. They are more common in men than women and are usually on the top of your head, on your shoulders or back. Mine was on my calf. It usually appears in people 60+ years old. I'm only 50. So this was a really odd type on melanoma for someone like me. Nodular melanoma happen in about 15% of all melanomas.
Superficial Spreading Melanoma is the most common type at about 70% of all melanomas. As the name suggests it spreads on the surface of the skin and does not penetrate deeply. It can happen in people of all ages and slightly more in females. In females it is more likely seen on the legs. In males it is more likely seen on the area between the neck and waist. But can be all of those places in either males or female. These melanomas can be any colour and usually have irregular borders. These can be itchy and grow fast.
Lentigo Melanoma usually show up on the face of middle aged or elderly people that have a lot of sun damage. They are about 10% of all melanomas. People think they are "sun spots". It has irregular borders and can be many shades of brown.
Acral Lentiginous Melanoma are about 5% of all melanomas. These show up on areas of the body that aren't as easily seen or no one thinks to look there for melanomas: palms of hands, soles of feet, in the mouth, nose, or female genitals, under or near fingernails and toenails. In the early stages can look like a bruise or nail streak.
For pictures you can go to SkinCancerNet: http://www.skincarephysicians.com/skincancernet/four_types.html